Cambridge International Examinations Cambridge International General Certificate of Secondary Education *1219785243* BIOLOGY 06/62 Paper 6 Alternative to Practical October/November 15 1 hour Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate. This document consists of printed pages and 2 blank pages. DC (NH/CGW) 2882/4 [Turn over
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3 1 During respiration, a chemical is produced that causes the indicator methylene blue to change from blue to colourless. Some students investigated the effect of temperature on the rate of respiration in yeast, using yeast and methylene blue. A ruler was used to measure 2 cm from the top of three test-tubes and a line was drawn on each test-tube. Yeast suspension with glucose was poured into each test-tube until it reached the line drawn on the test-tube. Three beakers were labelled: cold, warm and hot. One test-tube was placed in each container. A mixture of ice and water was placed into the beaker labelled cold, tap water at room temperature into the beaker labelled warm and hot water from a tap into the beaker labelled hot. A thermometer was used to measure the temperature in each beaker. The test-tubes were left for five minutes and then 1 cm 3 of methylene blue was added to each test-tube. A glass rod was used to stir the mixture so the methylene blue spread evenly. A stopper (bung) was placed in each test-tube and a timer started. The time for the methylene blue to become colourless was recorded. This was trial 1. The same procedure for trial 1 was repeated twice to give results for trial 2 and trial 3. Fig. 1.1 shows the temperatures of the water in each beaker and the times, in minutes and seconds, for each test-tube to become colourless. [Turn over
4 cold beaker warm beaker hot beaker 0 0 0 90 90 90 80 80 80 70 60 50 trial 1 70 60 50 trial 1 70 60 50 trial 1 40 40 40 0 trial 2 0 trial 2 0 trial 2 trial 3 trial 3 trial 3 Fig. 1.1 (a) Prepare a table to record the results of the investigation shown in Fig. 1.1. Read the temperature for each beaker and the times taken for the methylene blue to become colourless at each temperature. In your table: record the temperatures in degrees Celsius record the times in seconds. [6]
5 (b) (i) State a reason why the students took three readings for each temperature....[1] (ii) Calculate the average time for the methylene blue to become colourless at each temperature. Show your working and record your results in Table 1.1. Give your answer to the nearest whole number. Table 1.1 temperature / C working average [2] (iii) State one conclusion about the effect of temperature on the rate of respiration in yeast....[1] (c) (i) The method of timing how long it takes for the methylene blue in the three test-tubes to become colourless is a source of error. Suggest why....[1] (ii) Describe how you could improve the method to reduce this source of error....[1] [Turn over
6 (d) Some students investigated the effect of ph on the rate of respiration by measuring the volume of carbon dioxide produced by yeast in minutes. Their results are shown in Table 1.2. Table 1.2 ph average volume of carbon dioxide produced in minutes / cm 3 rate of carbon dioxide production / cm 3 per minute 4 6 0.2 5 12 0.4 6 36 1.2 7 54... 8 63 2.1 (i) Complete Table 1.2 by calculating the rate of carbon dioxide production at ph 7. Write your answer in the space in Table 1.2. Show your working in the space below. [1] (ii) Plot the data from Table 1.2 to show the effect of ph on the rate of carbon dioxide production by yeast. [4]
7 (iii) Describe and explain the trend shown by the results in Table 1.2 and the graph you have drawn....[3] [Total: ] [Turn over
2 Fig. 2.1 shows photomicrographs of two types of pollen grain, R and S. 8 X Y R S not to scale Fig. 2.1 (a) (i) Make a large drawing of pollen grain S. [3]
9 (ii) Measure the length of the line XY on Fig. 2.1. Include the unit. length of XY... Draw the line XY on your drawing, in the same position as on Fig. 2.1. Measure the length of XY on your drawing. Include the unit. length of XY on your drawing... Calculate the magnification of your drawing. Show your working. magnification x... [5] (b) (i) State two ways, visible in Fig. 2.1, in which pollen grain R is different from pollen grain S. Write your answers in Table 2.1. Table 2.1 feature pollen grain R pollen grain S.................. [2] (ii) Describe one feature, visible in Fig. 2.1, of pollen grain R that helps it to be dispersed....[1] [Turn over
(c) Some students placed samples of each type of pollen grain on a microscope slide and added a drop of dilute sugar solution. Pollen tubes started to grow. To find out which of the pollen tubes grew faster, students measured the length of the pollen tubes every 2 minutes for minutes. (i) Suggest how the pollen tubes could be measured using a microscope....[1] Their results are recorded in Table 2.2. Table 2.2 time / min length of pollen tubes / µm pollen grain R pollen grain S 2 0.5 0.4 4 1.8 1.5 6 4.2 3.9 8 12.6 13.4 18.8 21.1 12 24.9 29.6 14.2 36.8 16 36.6 44.2 18 41.9 52.8 48.5 59.8 (ii) Compare the growth of pollen grain S with pollen grain R, using the data from Table 2.2....[3]
11 (d) The plant that produces pollen grain R produces fruits that contain seeds. These fruits disperse the seeds by splitting along the edges, throwing out the seeds. The students counted the number of seeds in a random sample of 0 fruits. Fig. 2.2 is a frequency histogram of their results. 50 40 frequency 0 21 22 23 24 25 number of seeds per fruit Fig. 2.2 (i) Suggest how the students could collect a random sample and count the seeds accurately....[3] (ii) Identify the most frequent number of seeds in a fruit....[1] (iii) Suggest one reason why some fruits have a lower number of seeds than others....[1] [Total: ]
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